Road-making material.



. No Drawing.

lies in the application to an ordinary Mao.

p as

. the same.

j TAT are se aoan raanrne MATERIAL.

'at Vancouver, in the Province of British Columbia, Canada, haveinvented certain new and useful Improvements in R'oad- Makin Material,of which the following is a'spec' cation.

' This invention relates to an improved road" construction which isparticularly de-.

signed to form a simple and comparatively inexpensive roadway, thesurface of which will not be impaired by ordinary auto traiiic and thatwill be elastic and dustless.

The invention is particularly described in the following specification.

The essential principle of the invention adam or rock roadway of a novelbonding material that will compactly fill all the interstices of therock when the same is rolled. This bonding material is a mixture ofsawdust with a suficient amount of a bituminous material such as 'heavyroad oil (crude oil) or asphaltum or tar as will effectively cover thesurfaces of the rock, permeate the material of the sawdust and that willfill the interstices of The oil, asphaltum, or tar, is used as .a strongadherent material holding the interlocked particles of sawdust together,and .is not merely a medium in which a certain proportion of sawdust is1 embodied. If the oil is in excess it does not hold the particlestogether but serves as a lubricant permitting them to slide past oneanother under the rolling action of the traffic. The same principleshould prevail in the association of the bonding material of sawdust andoil with the rock. The pieces of rock are not merely associated in acomposition with oiland sawdust'but the rock must be strongly rolledtogether so as to have a minimum ofinterspace, and these interspacesmust be filled with tightly packed sawdust bound together with asphaltummaterial.

All road oils carry a large proportion of asphaltum or the like andwhile the more volatile and soluble oils may evaporate, or be washedout, sufiicient of the heavier insoluble parts remain to bind thesawdust together. 1 I

The preferred method of applying this bonding material is to take therock (broken tothe size as for an ordinary Macadam Specification ofLetters Patent.

Application filed Gctober 4.1913. Serial No. 793,332.

Eatent will compactly fill the interspaces of the rock when the roadwayhas been heavily rolled with as much of any heavy road oil, asphaltum ortar as will cover the surfaces of the pieces of rock, permeate thesawdust and fill the interstices of the same when it is tightly packedtogether. These proportions will vary according to the character of theroad required, the nature of the rock and of the sawdust. Thesematerials, in such proportion as will satisfy the above requirements,are thoroughly mixed together and-are spread upon the road, and. theroad is heavily rolled. The

result is a compact elastic. road bed, the.

wearing surface of which is the rock and the bonding material is thetightly packed, elastic, asphaltum-cemented saw dust. The same resultmay be obtained, although not so effectively, by spreading 'road) andsuchproportion of sawdust as the rock,-as in making an ordinary Macadamroad; thereafter spreadin sawdust over the rock and scarifying it toinsure that the sawdust works into the wide interstices of it. After thesawdust is thoroughly worked among the rock, the heavy oil, asphaltum ortar is spread over the rock and sawdust in sufiicient quantity topermeate the sawdust filling between the interstices, of the rock, andthe road surface is then heavily rolled to pack the rock tightlytogether and to compress the sawdust within its interstices.

It must be distinctly understood that the sawdust is not designed togive substance or body to a bonding material of asphaltum or othercomposition of matter, but the heavy oil is added to bind together :theclosely compressed sawdust.

It will, in all'likelihood, be found advisable to apply a top dressingof sand or fine rock crushings to the surface of the road bed when it isturned over for use, but this will not form a constituent part of theroad, but is merely applied to prevent the .asphaltum material fromsticking to the wheels of passing vehicles and possibly lifting the roadsurface.

Having now particularly described my invention, I hereby declare thatwhat I claim as new and desire to be protected in by Letters Patent, is:

1. A road making material, comprising broken rock and a filling for theinterstices of the closely packed rock said filling'com- 5 with abituminous material, to fill comprising sawdiist permeated with a bitumi-. In testimony iavhereof I aflix my signature nous Eaterial. I inpresence of two Witnesses.

2. road ma g -mauaerial comprising I broken rock with sufiicient savidust soaked GEORGE S Witnesses:

ROWLAND BRHTAiN, .MAY. WHYTE.

pactly the-interstices between the rock when the same has been heavilyrolled.

